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Z Old Physiology > Unit 3 > Flashcards

Unit 3 Flashcards

1
Q

Cardiac Cycle

A

all cardiac events that occur during one heartbeat

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2
Q

Contraction of atria or ventricles

A

Systole

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3
Q

Relaxation of atria or ventricles

A

Diastole

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4
Q

Why can cardiac muscle initiate its own rhythmic contractions without nervous stimulation?

A

“Leaky” cell membranes allow influx of Na+ and Ca2+ ions which slowly depolarize the cells to threshold, firing an action potential.

“Pacemaker” cells in the sinoatrial node depolarize fastest and control the rate of contraction of all other cardiac cells

The action potential moves relatively slowly through the atrioventricular node to ensure that atria contract first, and ventricles fill with blood before they contract

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5
Q

factors that affect cardiac contraction strength

A

inotropes

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6
Q

factors that affect heart rate

A

chronotropes

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7
Q

epinephrine (effect on heart)

A

increases heart rate

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8
Q

acetylcholine (effect on heart)

A

decreases heartrate (muscarinic receptors)

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9
Q

Atropine (effect on heart)

A

increases heartrate by cholinergic antagonistic action

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10
Q

calcium (effect on heart)

A

increases force of contractions

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11
Q

Potassium (effect on heart)

A

regulates heart rhythm

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12
Q

digitalis (effect on heart)

A

positive inotrope (increases contraction strength)

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13
Q

blood flow in the center of a vessel, not in contact with the endothelium

A

laminar flow

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14
Q

What components in blood affect viscosity?

A
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15
Q

How does blood vessel length affect blood flow?

A

longer vessels = slower flow rate because of drag on greater surface area of endothelium

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16
Q

What is wave summation?

A

when muscle is stimulated frequently enough that twitches overlap

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17
Q

What is the absolute refractory period?

A

the period during which APs can’t be generated no matter how strong the stimulus

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18
Q

How long is the total refractory period of cardiac muscle?

A

200-250 ms

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19
Q

What is an extrasystole?

A

an extra contraction

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20
Q

When is it possible to stimulate an extrasystole?

A
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21
Q

What is vagal escape?

A

sympathetic stimulation of the heart to increase rate and blood pressure in response to a muscarinic stimulation causing reduction of blood pressure

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22
Q

What causes vagal escape?

A

sympathetic reflexes

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23
Q

how many APs does the SA node generate per minute without external stimulation?

A

100

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24
Q

Which organelle in a cardiac muscle cell stores calcium?

A

sarcoplasmic reticulum

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25
Q

What are the different layers of “bundling” within a skeletal muscle?

A

A muscle is covered by epimysium and is a bundle of…

Fascicles which are covered by perimysium and are bundles of…

**Muscle fibers (muscle cells) **which covered by endomysium and are bundles of…

Myofibrils which are bundles of…

Actin and myosin proteins

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26
Q

What is the cell membrane of a muscle cell?

A

sarcolemma

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27
Q

What are the 3 types of muscle and their general functions and structure?

A

Skeletal - position and move skeleton, large, multinucleate, striated cells

Cardiac - pump blood (heart), short, branched, striated uninucleate cells connected by intercalated disks

Smooth - movement of material into, out of and within body, small, uninucleate, unstriated cells

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28
Q

What is the cytoplasm of a muscle cell?

A
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29
Q

What is the name and function of the structure that wraps around each myofibril like a piece of lace?

And its parts?

A

Sarcoplasmic Reticulum

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30
Q

Describe the T-tubules. What are they, what do they do and what is the structure they make up with the terminal cisternae?

A
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31
Q

What neurotransmitter is used at neuromuscular junctions?

A

Acetylcholine

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32
Q

What are 4 characteristics/abilities of muscle tissue?

A
  1. Can shorten (contraction)
  2. Can stretch/lengthen (relaxation)
  3. Elasticity (returns to normal)
  4. Excitability (can create APs or be stimulated by nerve)
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33
Q

What is a motor unit?

A

A unit in the somatic NS and musculoskeletal system consisting of a motor nerve and all the muscle cells it innervates

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34
Q

How many motor units per muscle?

How does this ratio affect control?

A
  • Varies greatly, but most muscles have > 1 motor unit
  • nerve to muscle cell ratios can be anything… 1:13, 1:137, 1:529, etc.
  • the fewer muscle cells per nerve, the greater the degree of fine control over that muscle
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35
Q

Describe the transfer of a signal between motor neuron and muscle cell at the motor end plate.

A
  1. AP travels to axon terminal of motor nerve
  2. Voltage-gated Ca channels open at synaptic knob, Ca diffuses in, attaches to synaptic vesicles
  3. Synaptic vesicles full of acetylcholine exocytosize to synaptic cleft and attach to chemically-gated Na channels
  4. Na diffuses in to create AP on muscle cell which travels deep into cell
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36
Q

What are the bundles of proteins within a single muscle cell called?

What 2 major proteins make them up?

And what is a single functional unit within this bundle called?

A

- Myofibrils

- Actin and Myosin

- Sarcomere

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37
Q

How are myofilaments laid out within a relaxed myofibril?

Describe it and draw it.

A
  • Alternating bands of thicker myosin and thinner actin myofilaments line the cell (w/ Z-discs intersecting actin and M lines intersecting myosin)
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38
Q

How is acetylcholine removed from the chemically-gated Na channels?

A

1) enzymatic breakdown via **acetylcholinesterase **into acetyl and choline
2) re-uptake into the pre-synaptic axon terminal

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39
Q

How does innervation of skeletal and cardiac muscle differ?

A
  • Each skeletal muscle cell is innervated by communication with a synapse
  • Many cardiac muscle cells are innervated by one synapse and communication via intercalated disks (gap junctions) between cells
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40
Q

How does an AP affect myofibrils of a muscle cell nearly simultaneously?

A

T-tubules extending deep into cell allow fast (extracellular, non-cytosolic) travel of ions to the deeper myofibrils

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41
Q

Describe the transmission of action potentials deep into muscle cells via T-tubules and the release of calcium from terminal cisternae of the sarcoplasmic reticulum.

Draw it.

A

1) APs begun by ACh at motor end plate travel along sarcolemma into T-tubules
2) APs cause voltage change at triad, opening Ca channels on terminal cisternae for diffusion of Ca into sarcoplasm

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42
Q

What are some functions of muscle?

A

1) produce movement
2) open and close passageways
3) maintain posture and stabilize joints
4) generate heat

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43
Q

What is the theory behind muscle contraction called?

Describe it.

A

Sliding Filament Theory

or Contraction Coupling Process

**- **Myosin pulls actin (z-lines) closer together

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44
Q

What is the functional unit of a muscle?

What is it made up of?

A

Sarcomere

  • Actin and myosin filaments
  • Z-lines bisect actin filaments
  • M-lines bisect myosin filaments
  • A-bands are areas where myosin is
  • I-bands are where it is not
  • H-zone is portion of A-band w/out actin
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45
Q

Describe the structure of actin and its accessory proteins.

Draw it.

A

2 strands of globular actin

2 strands of tropomyosin

Troponin complexes

46
Q

How does myosin bind to actin? Describe the process.

Draw it.

A

1) Ca ions bind to troponin complexes
2) Tropomyosin then moves away from myosin binding sites on actin
3) Myosin heads w/ actin binding sites move in and bind

47
Q

How is a myosin filament structured?

Describe and draw it.

A

Myosin filaments are made of many myosin molecules.

There is a “tail” of two strands twisted together and “heads” like two golf club heads at the end of the tail (AKA cross-bridge heads).

48
Q

Describe the contraction cycle.

Draw it.

A

1) Myosin heads bent w/ ATP attached, unbound to actin
2) Myosin hydrolyzes ATP, energy “cocks” head, myosin binds weakly to actin
3) “Power Stroke” - Ca signal moves tropo/tropo complex, P leaves myosin, heads re-bend pulling actin toward M-line, ADP leaves myosin
4) Myosin is bound to actin, ATP re-binds myosin, cycle repeats.

49
Q

What are some sources of ATP within the muscle?

A

1) stored ATP (lasts 6 seconds)
2) creatine phosphate (donates phosphate to ADP to make ATP, lasts 10 seconds)
3) cellular respiration ( 2 ATP glyc, 2 ATP krebs, 26 ATP ETC)

​​

50
Q

What is the force of contracting muscle and its opposing force called?

A

Contraction - muscle tension

Opposing force - load

51
Q

What is a single contraction-relaxation cycle in skeletal muscle called?

What are its parts?

A

Twitch

Latent Period - between muscle AP production and tension development

Contraction Phase

Relaxation Phase

52
Q

How can nervous signals cause contraction force increase?

A
  • by increasing frequency of APs stimulating muscle fiber to cause summation
  • increased AP frequency does not allow full relaxation between stimuli
53
Q

What is the state of continuous maximal contraction called?

And its two kinds?

A

Tetanus

incomplete or unfused tetanus - slight relaxation between stimuli

complete or fused tetanus - no relaxation

54
Q

How are graded muscle contractions of different strengths and durations created?

A

Recruitment of different types and numbers of motor units.

Low threshold neurons control fatigue-resistant slow-twitch minimal force fibers.

Medium threshold neurons stimulate fatigue-resistant fast-twitch oxidative-glycolytic fibers

High threshold neurons stimulate glycolytic fast-twitch fibers

55
Q

What kind of contraction creates force and moves a load?

A

Isotonic Contraction

56
Q

What kind of contraction creates force but does not move a load?

A

isometric contractions

57
Q

Describe the flow of blood from its entrance into the heart to its exit from the heart.

A
  1. Superior and Inferior Vena Cava
  2. Right Atrium
  3. Tricuspid Valve
  4. Right Ventricle
  5. Pulmonary Semilunar Valve
  6. Pulmonary Trunk & Arteries
  7. Lungs (pulmonary capillaries)
  8. Pulmonary Veins
  9. Left Atrium
  10. Biscuspid (Mitral) Valve
  11. Left Ventricle
  12. Aortic Semilunar Valve
  13. Aorta
58
Q

What is the primary function of the cardiovascular system?

A

Transporting materials to and from all parts of the body.

1) Nutrients, water, gases from outside
2) materials between cells
3) wastes from cells

59
Q

What are the 3 components of the cardiovascular system?

A

Heart

Blood Vessels

Blood

60
Q

What are the two circuites of the cardiovascular system?

A

Systemic

Pulmonary

61
Q

What are the serous membranes around the heart?

A

Visceral pericardium - directly on heart

Parietal pericardium - lines pericardial cavity

62
Q

What does an electrocardiogram look like?

Draw it.

A
63
Q

What does each part of the PQRST of an EKG represent?

A

P Wave - atrial depolarization (from SA node)

QRS Wave - ventricle depolarization (and atrial repolarization)

T Wave - ventricle repolarization

64
Q

What are the structures of the conduction system of the heart?

Draw them.

A

Sinoatrial (SA) Node - pacemaker (right atrium)

Atrioventricular (AV) Node - delays signal to ventricles by 2 ms so they contract after atria

Bundle of His - send signals from AV node to bundle branches

Left/Right Bundle Branches - run down IV septum to Purkinje fibers

Purkinje Fibers - conduct signals along walls of ventricles

65
Q

What is a miscommunication in the heart’s electrical system known as?

Where does it usually occur and why?

A

Fibrillation

Usually in left atrium because of distance from SA node

66
Q

How do the atrial and ventricular contractions move?

A

Atrial start superiorly and move inferiorly to move blood down into ventricles

Ventricular are opposite to move blood up and out semilunar valves

67
Q

Describe an action potential in electrical conduction cells of the heart.

Draw its graph.

A
  1. Increased Na permeability causes a constant drift from -60 mv resting state to threshold
  2. -40 mv threshold is reached, voltage-gated Ca channels open
  3. +20-30 mv max voltage is reached via Ca influx
  4. K efflux repolarizes to resting, no hyperpolarization
68
Q

Describe an action potential being created in a myocardial contractile cell.

Draw its graph.

A
  1. -90 mv resting state rises to -60 mv threshold due to Na influx
  2. voltage-gated fast Na and slow Ca channels open to depolarize cell to +30 mv
  3. fast Na channels close, slow Ca channels stay open, causing Ca plateau, lengthens abs. refractory period and allows for simultaneous contraction of multiple cells
  4. K+ efflux repolarizes
69
Q

What part of the cardiovascular system’s pressure is being measured when blood pressure is measured?

During what activity?

A

arterial pressure during ventricular activity

systole - contraction

diastole - relaxation

70
Q

What is pulse pressure?

Its ideal value?

A

Systolic minus diastolic

30-40 mm Hg

71
Q

What is cardiac output?

A

the amount of blood pumped out of the heart each minute

72
Q

How is cardiac output calculated?

What is the usual cardiac out put in an adult?

A

Heart Rate x Stroke Volume

(75 bpm x 70 mL = 5,250 mL)

about 5.2 L/min

73
Q

What happens to cardiac output if heart rate changes?

A

Cardiac output stays the same.

An increased HR means a decreased stroke volume, so CO stays same.

Decreased HR = increase SV.

74
Q

What is the amount of blood pumped out of each ventricle each beat?

A

Stroke Volume

about 70 mL

75
Q

What 3 factors affect stroke volume?

A
  1. Contractility -
  2. Preload - degree of stretch (Frank-Starling Law)
  3. Afterload - diastolic value
76
Q

What 3 factors affect peripheral resistance?

A
  1. diameter - smaller diameter = less laminar flow
  2. length - greater length = more drag against sides
  3. viscosity - more viscous = slower flow
77
Q

What are the 3 layers of a blood vessel?

A
  1. Tunica Interna - endothelium
  2. Tunica Media - smooth muscle
  3. Tunica Externa - CT
78
Q

What are the differences between arteries and veins?

A

Arteries

  • away from heart
  • small lumen
  • higher pressure
  • thicker tunica media
  • maintain shape

Veins

  • towards heart
  • large lumen (contain 60% of blood)
  • low pressure
  • thin tunica media
  • shaped by surrounding tissues
  • have valves
79
Q

What are the different types of arteries?

A

Elastic - aorta, pulmonary, their branches

**Muscular - **AKA medium or distributing, renal, brachial, femoral, etc.

**Arterioles - **just before capillary beds, control BP and capillary flow via vasoconstriction/dilation

80
Q

What are the different types of veins?

A

Large Veins - sup. & inf. vena cava (0-5 mm Hg)

Medium Veins - brachial, femoral, renal, etc. (10 mm Hg)

Venules - drain capillary beds (20 mm Hg)

81
Q

What are the three types of capillaries and where are they found?

A
  1. **continuous - **solid endothelium (common)
  2. fenestrated - holes in endothelium (kidneys)
  3. sinusoidal - very porous endothelium (spleen, liver, red bone marrow)
82
Q

What are the two forces that influence movement of substances between capillaries and tissues?

Which forces fluid out of capillaries and which draws fluids back in?

What is each based on and can each change?

A

Blood Hydrostatic Pressure - normal blood pressure based on pumping of heart, descreases as distance from heart increases, pushes fluids out of capillaries

**Blood Osmotic Pressure - **keeps fluids in, based on non-diffusable solutes, doesn’t change

83
Q

Draw the capillary with its differing pressures on each end, showing how they influence movement of substances into and out of tissues.

A
84
Q

What is the composition of blood?

Components and percentages.

A

**Plasma (55%) **- water, ions, hormones, gases, wastes

Formed Elements (45%) - RBCs (44%), WBCs and platelets (1%)

85
Q

What are the 5 functions of blood?

A
  1. Transport
  2. Temperature Control
  3. Immunity
  4. pH Control
  5. Blood Clotting
86
Q

Describe erythrocytes, their functions and characteristics.

A
  • released mature from bone marrow without nucleus or organelles

**- binconcave **for flexibility and surface area

  • live 100-120 days b/c of lack of organelles
  • contain hemoglobin to carry oxygen and carbon dioxide
87
Q

Describe hemoglobin, its structure and function.

A
  • a quaternary protein structure
  • consists of four 4 Heme groups and 4 Globin proteins

- carries O2 and CO2 separately

- 200-250 million per RBC, so on RBC can carry both gases

88
Q

Which gas loads more easily onto hemoglobin?

Describe loading of gases.

A

CO2loads more easily

first O2 loads easily, second requires pressure, 3rd/4th are easy

89
Q

Describe RBC movement through capillaries and how it is advantageous to function.

Draw it.

A

Biconcave RBCs bend into kidney bean-like shape and move slowly through capillaries to allow for gas exchange.

90
Q

How does the body compensate for elevational changes in oxygen pressure?

A

It increases erythropoiesis at higher elevations to increase its ability to transport oxygen.

91
Q

How are erythrocytes broken down and removed from the body?

A
  • primarily in spleen, also in liver if necessary
  • reticular fibers of these organs create network for flexible RBCs

- old, inflexible RBCs phagocytized by WBCs

- Hemoglobin is recycled

92
Q

Describe hemoglobin recycling.

A
  • Broken into Heme and Globin
  • Heme is reused or turned into bilirubin by spleen, sent to liver and made into bile salts (either stored in GB or straight to SI)
  • Globin is re-used or broken down into amino acids
93
Q

Name the two subcategories and 5 types of leukocytes.

What are the characteristics of the 2 subcategories?

A

**Granulocytes (granules, lobed nuclei)- **basophils, neutrophils, eosinophils

**Agranulocytes (no granules, large, unlobed nuclei) - **lymphocytes, monocytes

94
Q

What is most common leukocyte?

Describe it.

A

Neutrophil

  • lobed nuclei
  • phagocytic
  • pink granules
95
Q

What is the 2nd most common granulocyte?

Describe it

A

Eosinophil

  • phagocytic
  • involved in parasitic infection and allergy
  • red/orange granules
96
Q

What is the least common leukocyte?

Describe it.

A

Basophil

**- **involved in allergy

  • releases histamine in inflammation and heparin for anti-coagulation
  • blue-purple granules
97
Q

What is the 2nd most common WBC?

Describe it.

A

Lymphocytes

- large central nuclei almost to plasma membrane

  • two kinds, B and T
  • specific to certain pathogens, have ‘memory’ for antigens

T Cells (thymus)

- attacks and kills cells

  • helper T cells help lymphocyte production

B Cells (bone)

  • produce antibodies
  • mark pathogens for removal
98
Q

What is the largest WBC?

Describe it.

A

Monocyte

- phagocytic

  • large, kidney-shaped nucleus
  • migrates to tissues to become macrophage
99
Q

What is hematocrit?

A

the volume percentage of RBCs in blood

about 45% for men

about 40% for women

100
Q

How does blood typing work?

Draw out the chart.

A

A has A-antigen and B-antibody

B has B-antigen and A-antibody

AB has both antigens and neither antibody

O has neither antigen and both antibodies

101
Q

Describe how Rh factor works.

A

Rh factor is a surface antigen on RBCs.

Rh+ people have it, Rh- people don’t

Rh+ people can receive either blood type because they do not create antibodies to Rh factor.

Rh- people can only receive Rh- blood because they DO produce antibodies. (They can receive + blood once, but then are sensitized).

102
Q

What are the names for the surface antigens and their antibodies in ABO typing?

A

Agglutinogens (antigens)

**Agglutinins **(antibodies)

103
Q

What are platelets called and where do they come from?

A

Thrombocytes

**- **from megakaryocytes

104
Q

What is blood clot formation called? Describe its 3 steps.

A

Hemostasis

**1. Vascular Spasm **- damaged endothelium releases vasoconstrictors

**2. Platelet Plug - **releases platelet-activating factor (PAF) which attracts platelets

3. Coagulation - fibrin net forms around platelet plug

105
Q

What is a floating blood clot called?

A

Thrombus

106
Q

What is the process of fibrin net breakdown and release of platelets?

A

Fibrinolysis

107
Q

What are the two types of coagulation and their characteristics?

A

Intrinsic

  • natural
  • internal
  • slow

Extrinsic

**- **fast

  • usually due to trauma
108
Q

What is the important protein in coagulation called?

Describe its creation.

A

Thrombin

  1. Ca++ acts on Factor X
  2. Factor X becomes active
  3. Ca++ acts on Active Factor X
  4. Active factor X acts on Prothrombin
  5. Prothrombin converts into thrombin
109
Q

What molecules does thrombin act on to aid in clotting and clot breakdown?

A

Clot Formation

  1. thrombin acts on fibrinogen to form **fibrin **and Factor XIII to form Active Factor XIII
  2. Fibrin plus Ca++ and active factor XIII forms cross-linked fibrin net around the platelet plug

Clot Breakdown

  1. thrombin acts on plasminogen to form plasmin
  2. plasmin performs fibrinolysis on cross-linked fibrin net, breaking it down to release platelets
110
Q

what are the stem cells that blood cells come from?

A

hemocytoblasts

hematopoietic stem cells

111
Q

what is the pH range of blood?

A

7.35-7.45

112
Q
A

Z Old Physiology (7 decks)

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